The invention relates to a non-volatile memory, and in particular, to a technology effective when applied to a non-volatile memory, such as a flash memory (flash EEPROM), and so forth, capable of being supplied with two varieties of externally supplied voltages.
According to the results of studies conducted by the inventors, the following technology in connection with a non-volatile memory is conceivable.
For example, as for the non-volatile memory capable of being supplied with two varieties of the externally supplied voltages, such a technology as disclosed in Patent Document 1 can be cited. The technology disclosed in Patent Document 1 has a configuration in which two varieties of supplied voltages (Vcc), that is, 5V and 3V are supplied from outside, and internal circuits are arranged to operate with an internal operation voltage at 3V. The internal operation voltage is switched over with a threshold voltage to determine whether the externally supplied voltage is to be stepped down to the internal operation voltage, or to be supplied as the internal operation voltage. The externally supplied voltage is stepped down to 3V and supplied the stepped down voltage to the internal circuit when 5V is supplied as the externally supplied voltage. Or the externally supplied voltage is supplied to the internal circuit when 3V is supplied as the externally supplied voltage. Further, a high voltage (Vpp) necessary for writing and erasing is also supplied from outside.
[Patent Document 1]
Japanese Unexamined Patent Publication No. Hei 5 (1993)-12890